A group of girls in Claires town have noticed strange sights and sounds coming from the tree house where their club meets. Is it a rival boys club trying to scare them away? Or is it a ghost? The girls ask Claire to tackle the mystery--and Kaz hopes to finally find the rest of his missing family members!

For all the books they have written, Andy is the narrator and Terry is the illustrator, but when Terry tries to narrate too, the story goes out of control and they must evade the Story Police, who want to arrest them for crimes against storytelling.

Andy and Terry live in a 130-story treehouse. It used to be a 117-story treehouse, but they added another 13 stories. It has a soap bubble blaster, a time-wasting level, a 13-story igloo, the GRABINATOR (it can grab anything from anywhere at any time). It is a toilet paper factory, and an extraterrestrial observation center for observing aliens. As it turns out, though, it's Andy, Terry, and Jill who are being observed and then abducted by a giant...

"It's the night before Christmas but Andy and Terry aren't ready yet! They haven't written their letters to Santa, they haven't sung any carols or hung their stockings, and now Mr. Big Nose wants their next book done by tomorrow. When Santa Claus's sleigh crash-lands in the treehouse, the reindeer become tangled in the branches and Santa falls into the cloning machine. With dozens of Santas running around and no way to tell which one's the real one,...

Domino builds a tree house in his backyard, followed by a tree cottage, and then a tree mansion, but he never seems to be happy with what he has.

"When Andy develops a severe toothache that prevents him from writing new jokes for their book, Terry uses their fantastical treehouse's money-making machine funds to purchase a Joke Writer 2000, with unexpected results." --